What is possible depends on your definition of “number”, for example the Unicode digits mentioned only match \d (digit) in some Regex implementations. And some cultures don’t have digits, for example Roman “Ⅴ” and old Italic “𐌡” (both mean 5 and look like an incoming flying goose) are numerals and never pass as \d. And Egyptian hieroglyphs 𓆏 (frog) or 𓆐 (tadpole but looks more like a parrot to me) can mean 100,000 but I haven’t seen them called numerals or digits. Neither the eel-like 𔗄 Anatolian hieroglyph for 1000.

I focused on strings that a computer might spit out when asked to print a float but that might include “-Inf” (rooster in grass?), which mathematicians don’t consider a number. However, they consider √7̅ (flying swan) a number, also “φ” (flamingo) aka golden ratio, equal to (√5̅+1)/2, and even complex numbers like -5+7i (flying bird with ornate tail). If you imagine a proper vertical fraction, ¼𝑒 (approx. 0.67957) could be a more detailed, wading flamingo. Coders will know what number -0xD7 (yet another sideways nesting/flying bird) is. And in some electrical engineering software, 1M7 (ostrich showing off its wings) means 1.7 million, 1p7 means 1.7 trillionths and 87j (rotate 90° right to see a chicken pecking at a seed) is the standard way to write “amplitude 87, phase 90°” - “j” is used for √-̅1̅ because “i” means current. However, most software, and likely this form, won’t accept non-Latin numbers, math symbols and engineers’ shortcuts (maybe the e/E for ⏨-exponent).